Finger identification apparatus

ABSTRACT

An identification apparatus that keeps the conditions for imaging uniform among successive identifications and requires a user to perform only a series of simple maneuvers. An identification apparatus comprising a guide member, a light source, and an imaging unit. The guide member includes a pattern or a structure that inspires a user to position his/her finger thereon or to approach his/her specific finger region thereto. A contact member such as a button switch is preferably located at a position in the guide member at which a fingertip is to be positioned. An optical opening is formed at a position coincident with a position at which a portion of a finger to be imaged for identification should be placed. The light source radiates near-infrared light through the portion of the finger to be imaged. The imaging means acquires an image of the finger, and the apparatus compares the image to previously registered images. The apparatus may also include dual light sources power saving functionality, and means for limiting the interference of external light sources.

CROSS REFERENCE FOR RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.11/976,528 filed on Oct. 25, 2007 now U.S. Pat. No. 7,561,257, which isa sibling application of U.S. application Ser. No. 11/976,529 also filedon Oct. 25, 2007, both of which are Continuations of U.S. applicationSer. No. 11/187,820 filed on Jul. 25, 2005, now U.S. Pat. No. 7,310,133,which is a Continuation of U.S. application Ser. No. 10/142,894 filed onMay 13, 2002now U.S. Pat. No. 6,970,234. Priority is claimed based onU.S. application Ser. No. 11/976,528 filed on Oct. 25, 2007 and U.S.application Ser. No. 11/976,529 filed on Oct. 25, 2007, both of whichclaim the priority of U.S. application Ser. No. 11/187,820 filed on Jul.25, 2005, which claims the priority of U.S. application Ser. No.10/142,894 filed on May 13, 2002, which claims priority from JapanesePatent Application No. 2001-218949 filed on Jul. 19, 2001, the contentof which is hereby incorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an identification apparatus foridentifying an individual using vital information, and, moreparticularly, the present invention relates to a finger identificationapparatus that utilizes a hemal pattern of a finger and methodstherefor.

2. Description of the Background

An individual identification technology is expected to enable the safemanagement of property and/or information. In particular, living body(personal) identification technologies that utilize parts of a humanbody as a key are beginning to attract attention. One reason for this isbecause a living body identification technology has a reduced chance foran illegal access to property or information resulting in a loss orrobbery as compared to conventional technologies for managing propertyand information using a password or a key. Living body identificationtechnologies include various techniques based on a fingerprint, a face,an iris, or a hemal pattern of a hand or a finger.

Among these techniques that are currently under study, theidentification technique utilizing a hemal pattern of a finger isadvantageous in that: (1) the technique reduces a user's reluctance toundergo identification because the technique is not associated withcrime (unlike a technique utilizing a fingerprint); (2) the techniquedoes not require direct irradiation of light into an eye (unlike atechnique utilizing an iris); and (3) the technique reduces thepossibility of forgery because it reads an internal feature of a livingbody instead of a superficial feature thereof.

The process for identifying an entity utilizing a hemal pattern of afinger will be described below. Initially, a light source for radiatingnear-infrared light is made available, and a camera is placed facing thelight source so that the camera can pick up only light emanating fromthe light source image. The camera is provided with an optical filterthat passes light with wavelengths which fall within the near-infraredband. For identification, a finger is interposed between the camera andlight source in order to image the finger. Since hematic componentsabsorb near-infrared light efficiently, the digital blood vessels do nottransmit light and are therefore visualized dark (i.e., appear dark inthe resultant image). The resultant image of a hemal pattern is thencompared with an image of a registered pattern, whereby individualidentification may be performed.

In order to correctly determine a correspondence between a hemal patternand a registered pattern, an image must be produced under the sameconditions for imaging between registration and identification. Forexample, if a finger is turned, a visualized hemal pattern is quitedifferent from a registered pattern. As long as a finger is displaced orturned with its surface to be imaged held unchanged, an image of a hemalpattern produced during identification can be corrected readily throughimage processing. However, if a finger is so turned that the surfacethereof is reversed from the dorsal side to the ventral side or viceversa, an image of a hemal pattern cannot easily be corrected becausesome blood vessels are unknown.

For example, an identification apparatus that utilizes the hemal patternof the palm of a hand directs a user to hold a guide bar with his/herfour fingers for positioning. The position of the palm of anindividual's hand to be imaged is thus made invariable. However, as faras the digital blood vessels are concerned, if a user holds the bar orthe like with his/her fingers, or, if a user stresses his/her fingers insome way, the digital blood vessels are compressed (as described above).Consequently, part of a hemal pattern may be missing or obscured.Another conceivable method is such that a guide rail or the like isincluded and a user is asked to place his/her fingers at a specifiedposition on the guide rail. However, this method requires a user tolearn how to place his/her fingers correctly. This means that noteverybody can easily use the apparatus.

Moreover, a visualized hemal pattern varies depending on the posture ofa finger inserted in an identification apparatus. For example, when afinger extended excessively with force has the blood vessels thereofcompressed due to the epidermal stress, part of a hemal pattern may bemissing. When extraneous light illuminating the entire identificationapparatus changes, the brightness or contrast of a produced imagevaries. This may adversely affect precision in identification.Specifically, near-infrared light contained in ordinary sunlight orillumination light may adversely affect visualization of a hemalpattern.

SUMMARY OF THE INVENTION

Accordingly, the present invention preferably provides a low-costidentification apparatus that keeps the conditions for imaging uniformamong identifications and directs a user to perform only a series ofsimple maneuvers. The related arts fail to guarantee that the conditionsfor imaging are the same among identifications.

In order to address one or more of the above objectives, according tothe present invention, there is provided a finger identificationapparatus comprising: a guide unit; a switch member; a light source; animaging unit; and an identifying unit. The guide unit helps position afinger for identification. The switch member is preferably turned on oroff with the fingertip. The light source that radiates transmissivelight which is transmitted through a finger is placed opposite theimaging unit with a space for finger insertion located therebetween.When the switch member is turned on, the identifying unit performsidentification on an image produced by the imaging unit.

Additionally, according to the present invention, there is preferablyprovided a finger identification apparatus comprising: a guide unit; alight source; an imaging unit; and an identifying unit. The guide unithelps position a bent finger. The light source that radiatestransmissive light which is transmitted through a finger is placedopposite the imaging unit with a space for finger insertion locatedtherebetween. The identifying unit performs identification on an imageproduced by the imaging unit.

The use of the present invention preferably leads a finger smoothly (andrepeatably) to a specific position and orientation. Furthermore, sincethe digital blood vessels are not compressed, a resultant image may becollated with a registered image on a stable basis. This results inmarkedly improved precision in identification.

BRIEF DESCRIPTION OF THE DRAWINGS

For the present invention to be clearly understood and readilypracticed, the present invention will be described in conjunction withthe following figures, wherein like reference characters designate thesame or similar elements, which figures are incorporated into andconstitute a part of the specification, wherein:

FIG. 1 shows an example of an apparatus according to the presentinvention;

FIG. 2 shows an example of the configuration of an apparatus accordingto the present invention;

FIG. 3 shows an example of a process flow performed by software used toimplement the present invention;

FIG. 4 shows an exemplary cross-section of a structure which is includedin an apparatus and into which a finger is inserted;

FIG. 5 shows an exemplary button switch;

FIG. 6 shows an exemplary finger rest;

FIG. 7 shows another example of an apparatus according to the presentinvention;

FIG. 8 shows an example of the elements included in an optical systemused to implement the present invention;

FIG. 9 shows an example of a processing flow performed by software usedto perform light level control according to the present invention;

FIGS. 10A and 10B show an exemplary device for measuring the thicknessof a finger according to the present invention;

FIG. 11 includes three side views of a finger identification apparatusaccording to the present invention;

FIG. 12 is a perspective view showing the assembly of components of afinger identification apparatus according to the present invention;

FIG. 13 shows a cross-section of a structure which is included in anapparatus in accordance with a second embodiment and into which a fingeris inserted; and

FIG. 14 shows an example of a finger identification apparatus includinga keypad.

DETAILED DESCRIPTION OF THE INVENTION

It is to be understood that the figures and descriptions of the presentinvention have been simplified to illustrate elements that are relevantfor a clear understanding of the present invention, while eliminating,for purposes of clarity, other elements that may be well known. Those ofordinary skill in the art will recognize that other elements aredesirable and/or required in order to implement the present invention.However, because such elements are well known in the art, and becausethey do not facilitate a better understanding of the present invention,a discussion of such elements is not provided herein. The detaileddescription will be provided hereinbelow with reference to the attacheddrawings.

FIG. 1 schematically shows an identification apparatus 100 according tothe present. The body of the apparatus is broadly divided into a lightsource unit 102 and an imaging unit 104. A space is created between thelight source unit 102 and the imaging unit 104. For identification, afinger is inserted into this space. The light source unit 102 preferablycovers over the space into which a finger is inserted and intercepts(shields) illumination light radiated from the ceiling or other externalsource to prevent a direct invasion of the light into the imaging unit.In the FIG. 1 embodiment, the space is not enclosed with a side wall.Alternatively, the space may be enclosed with one or more side walls inorder to hinder lateral invasion of extraneous light. In this case, theside walls are preferably coated with a dye such as an anti-reflectioncoat in order to prevent irregular reflection of near-infrared light, orthe side walls are preferably made of an anti-reflection material. Thisis intended to improve precision in identification.

The light source unit 102 has a light source 106 which radiatesnear-infrared light whose wavelengths are about 810 nanometers (nm)towards a camera 114 included in the imaging unit 104. A finger isinserted into the space between the light source 106 and camera 114,whereby near-infrared light is transmitted through the finger and pickedup the camera 114. Consequently, the hemal pattern of the finger isimaged. A guide groove 112 helps the user intuitively understand thecorrect position at which a finger should be located and the directionin which the finger should be oriented. A button switch 108 ispreferably located at a position at which a fingertip reaches when afinger is placed along the guide groove 112.

An opening 110 is located to coincide with a portion of the fingerincluding the first and second joints thereof. The opening 110 iscovered with a transparent glass plate, a transparent acrylic plate, orother material which passes light and prevents invasion of foreignobjects into the inside of the identification apparatus. The camera 114requires an optical filter that transmits only light whose wavelengthsfall within the near-infrared band. An optical filter plate may besubstituted for the glass or acrylic plate, whereby the capabilities ofthe glass or acrylic plate and of the optical filter can be integrated.

The identification process is initiated when a user presses the buttonswitch 108. The maneuver of pressing a button is an action peopleperform frequently in their daily lives. Therefore, a user shouldquickly get accustomed to this maneuver of pressing a button. Every timea user places his/her finger in a natural manner so as to press thebutton 108, the user's fingertip is located at a substantially fixedposition. In this way, the finger can be smoothly placed at a positionwhich can be repeated by the finger.

Once the fingertip is positioned, the finger is guided along the guidegroove 112. The direction in which the entire finger is oriented isdetermined accordingly. A region of the finger lying over the opening110 is thereby determined, and a range thereof to be imaged is nearlyuniquely determined. Moreover, when the user presses the button 108, thefinger joints are bent in a fixed direction. The ventral part of thefingertip is naturally oriented in a direction perpendicular to adirection in which the button is dented. If a finger is turned sideways,the surface of the finger to be imaged may be changed, that is, thedorsal part of the finger may be imaged at one time, and the ventralpart thereof may be imaged at another time. However, this will not takeplace because of the bending action.

When a user presses the button 108 with his/her finger, the finger isbent naturally. The epidermis of the user's hand other than theepidermis of the finger will not be stressed. Therefore, the digitalblood vessels will not be compressed, and no part of the hemal patternwill be missing. Moreover, as long as the finger is bent naturally, thefinger will not touch the glass plate covering the opening 110.Therefore, the possibility that a finger touches the glass plate andthat the digital blood vessels are compressed or the glass plate getsdirty will be reduced.

As long as the position at which a finger is placed is nearly fixed, thearea of the opening 110 may be made sufficiently small so that theopening 110 is blocked with a finger. If extraneous (external) light canbe blocked, a change in brightness or contrast caused by the extraneouslight can be prevented. In the conventional methods, because theposition at which a finger is placed is not fixed, the opening is maderather large in order to image a wide area on the finger. A portion ofthe image depicting the same hemal pattern as the one visualized duringregistration must then be searched. Therefore, high-cost hardware forcomputation is needed to search the same hemal pattern as the onevisualized during registration. Since the conventional opening is large,extraneous light easily enters. An identification apparatus inaccordance with the conventional method is therefore susceptible to“noise”. This drawback is addressed through the inclusion of the button108.

Moreover, the conventional identification technique based on a hemalpattern of a finger does not present a means for requesting the start ofthe identification process such as a switch to be manipulated by a user.The identification apparatus itself determines the start of theidentification, which may confuse some users. The inclusion of thebutton switch 108 itself is therefore effective in improvingmaneuverability.

It should be noted at this time that the guide groove 112 is not limitedto the illustrated shape. Moreover, a finger need not always touch theguide groove 112. For example, a wire-like guide or a guide shaped(e.g., like a finger rest) will do. In short, something capable ofguiding a finger unidirectionally is sufficient for the presentinvention.

FIG. 11 includes a top and two side views of an alternative embodimentof the present invention from that shown in FIG. 1. As shown in FIG. 11,the distance from the upper part of the structure to the lower partthereof at the apparatus opening is different from the space createdbetween the upper and lower parts at the deep end of the apparatus.Moreover, the surfaces of a light source 106 included in the upper partand of the opening 110 included in the lower part are arched in thisembodiment. The curvature of the arched surface of the upper part ispreferably larger than that of the arched surface of the lower part.Because of this design, when a finger is inserted into the structure,even if the ventral part of the finger is oriented sideways orobliquely, the orientation of the finger is corrected smoothly so thatthe ventral part of the finger will face down as the finger is advancedto the deep end of the space. This is because the space gets narrowertowards the deep end thereof. Furthermore, near-infrared light emanatingfrom the light source 106 is radiated evenly because of the curvature.Moreover, the distance from a camera 114 to any point in the opening 110is uniform. This leads to identification with higher precision.

FIG. 2 is a schematic block diagram showing the configuration of anidentification apparatus according to the present invention. A finger ofa hand 200 is inserted in a space created between a light source 106 anda camera 114. With a press of a switch 108, an image signal representinga hemal pattern is acquired. The image signal transferred from thecamera 114 is converted into digital data by an image capturing device202 and is stored in a memory 210 via an input/output interface 206 of acomputer 204. The switch 108 is connected to the computer via aninput/output interface. The on/off state of the switch 108 is stored inthe memory 210.

The instant the switch 108 is turned on, an interrupt signal isgenerated and transmitted to a CPU 208. When the CPU 208 confirms thatthe switch 108 is turned on, or when the CPU 208 senses generation ofthe interrupt signal indicating that the switch 108 is turned on, theCPU 208 activates and runs a software program that performsidentification. Based on the results of the identification performed bythe program, the CPU 208 executes any of various control sequences.Namely, the CPU 208 may display the result on a display device 212 ortransmit an appropriate instruction signal to a control target 216, forexample, that a door should be opened or closed. A keyboard 214 may beused to enter auxiliary information concerning identification, forexample, a password.

FIG. 12 is a perspective view showing exemplary components of the fingeridentification apparatus shown in FIG. 11 and FIG. 2 which are to beassembled.

FIG. 3 shows an example of a processing flow performed by software runby the hardware, or especially, the CPU 208. During processing 300, theentire hardware is initialized, and initial values are assigned totemporal variables needed to run the program. Once hardwareinitialization is complete, the program preferably becomes idle andwaits until the switch 108 is turned on (302). When the switch 108 isturned on, an image of a finger picked up by the camera 114 is stored inthe memory 210 (304). Image processing is performed on the stored imagedata in order to extract the features of a hemal pattern (306). Aregistered pattern to which the hemal pattern corresponds is searchedfor, or in other words, the hemal pattern is collated with registeredpatterns (308). If any registered pattern corresponds to the hemalpattern (310), a signal indicating that a correct access authority isidentified or identification data concerning an identified individual istransmitted to a control target such as equipment or a software programthat requires identification (312).

A standby state is then preferably re-established and retained until theswitch is activated again. The power supply of the hardware may also beturned on or off responsive to the on/off operation of the button switch108. When the button switch 108 is pressed, the power supply ispreferably turned on. The foregoing processing flow is performed exceptstep 302 until step 310 is completed. If identification succeeds, thesteps ending with step 312 are executed successively. Thereafter, thepower supply is turned off again. Thus, power consumption required in astandby state can be minimized.

The on/off operation of the light source may also be controlled. Whenthe button switch 108 is turned on, the light source is preferablyturned on at the same time. When identification is completed, the lightsource is turned off at the same time. With respect to the on/offoperation of the power supply of the apparatus, it may take an extendedamount of time to activate the apparatus, although this factor dependson the configuration of the apparatus. Therefore, when an emphasis isput on timing, efforts should be made to save power required by thelight source alone. The on/off operation of the light source may bephysically interlocked with the on/off operation of the switch 108. Aswitching circuit including relays and transistors may be connected tothe input/output interface 206 of the computer 204, whereby a switchused to turn on or off the light source may be electronicallycontrolled.

The above type of electronic control circuit having a switch turned onor off quickly can also be used to control so-called “pulse widthmodulation” (PWM). Consequently, the brightness of the light source canbe controlled stepwise. The thickness of a finger differs from person toperson. As long as an amount of light is fixed, whether a hemal patternis successively visualized depends on the person. Through the step-wisecontrol of the amount of light, a finger may be imaged continuouslyuntil the hemal pattern is successfully visualized. This leads toimproved precision in identification. In addition, if a sensor formeasuring the thickness of a finger is included is in the apparatus, therelationship between the thickness of a finger and an optimal amount oflight is calculated in advance and stored. Thus, an optimal hemalpattern can be visualized by picking up the least number of images.

FIG. 9 is a flowchart describing light level control dependent upon thethickness of a finger. During processing 900, the entire hardware isinitialized, and initial values are assigned to temporal variablesneeded to run the program. When hardware initialization is completed theprogram becomes idle and waits until the switch 108 is turned on (step902). When the switch is turned on, a sensor or the like is used tomeasure the thickness of a finger. A look-up table in which a set of thethickness values and initial light level values is recorded in advanceis preferably used to determine an initial amount of light that is toemanate from the light source 106. Thereafter, a finger is imaged usingthe camera 114, and the image data is stored in the memory 210 (step906). The stored image data is subjected to feature extraction 908 thatextracts the features of a hemal pattern, and a determination is made asto whether a hemal pattern was correctly visualized (step 912).

If a hemal pattern is not visualized, the amount of light is changed(step 910), and image data is fetched from the camera again. As for thedirection in which the amount of light is changed (e.g., up or down),when an image of a finger is too bright, it signifies that the amount oflight is so large as to cause saturation. The amount of light istherefore reduced. In contrast, when the image of a finger is too dark,it signifies that the amount of light is presumably so small as to lowera signal-to-noise ratio relative to transmissive light. The amount oflight is therefore increased. The brightness of a finger image ispreferably calculated using an average of pixel values.

Thereafter, a registered pattern to which the visualized hemal patterncorresponds is searched for, that is, the visualized hemal pattern iscollated with the registered patterns (step 914). If the visualizedhemal pattern corresponds to any registered pattern (step 916), a signalindicating that a correct access authority is identified oridentification data concerning an identified individual is transmittedto a control target, that is, equipment or a software program thatrequires identification (step 918). A standby state is then establishedagain and retained until the switch is activated.

FIG. 10A and FIG. 10B illustrate an exemplary method for measuring thethickness of a finger without using a sensor. FIG. 10A shows a planethat contains a light source 106 and that is imaged by a camera opposedto the light source. A light source 106 is located in the center of theplane and enclosed with a coating 1000 of a dye that suppressesreflection of near-infrared light or absorbs near-infrared light.Bar-shaped markings 1002 made of a material that efficiently reflectsnear-infrared light are formed on the coating 1000. When the lightsource glows, the contrast between the coating 1000 and the markings1002 becomes distinct. When the plane containing the light source isimaged using the camera, the difference in luminance between the coating1000 and the markings 1002 is intensified.

When a finger 200 is placed in front of the light source as shown inFIG. 10B, an area behind which the markings are hidden by the fingervaries depending on the thickness of the finger. The difference inluminance between a portion of an image of a finger depicting a bloodvessel and another portion thereof depicting no blood vessel is notintensified to a large degree. When a finger hides part of the markings1002, the difference in luminance of the part of the markings from thecoating is nullified. Coordinates indicating each point at which theintense difference in luminance terminates delineate the finger. This isachieved through very simple difference processing.

In order to measure the thickness of a finger, at least two markings arepreferably needed. Since a finger has joints, the thickness thereof isuneven. Therefore, when four markings are used as illustrated, thethickness of a finger can be determined more accurately. Moreover, whenthe four markings are used, even if a finger is inserted while beingslightly inclined, the inclination can be detected.

FIG. 4 is an enlarged view of a structure into which a finger isinserted that is included in an identification apparatus according to anembodiment of the invention. A near-infrared light source 106 is locatedin the upper part of the structure, and an optical opening 110 is formedin the lower part thereof. A camera 114 is located below the opening. Atouch portion 400 of a button switch is pressed with a finger. When thetouch portion 400 is pressed while being touched directly with a finger,a contact switch 108 is turned on. The contact switch 108 is preferablyrealized with a pushbutton with a spring. When the contact switch 108 ispressed, the contact switch conducts. When the contact switch 108 isreleased, the spring automatically returns the switch to the initialposition, isolating the contacts. When the opening 110 and button 400are arched as illustrated so that a finger will be bent naturally, afinger is bent without fail. Consequently, the probability that part ofa hemal pattern is missing because the digital blood vessels arecompressed is greatly reduced. Moreover, when a glass plate covering theopening 110 is located at a lower position or a finger rest 402 isformed, the root of the finger floats relative to the opening 110.Consequently, compression of the blood vessels occurring when a fingercomes into contact with the opening 110 can be more effectivelyprevented.

FIG. 13 is an enlarged view showing a lateral side of another embodimentof the present invention having a structure in which a finger isinserted. Compared with the structure shown in FIG. 4, the position of abutton switch 1301 is different from the position of the button switch400. Unlike the button switch 400 shown in FIG. 4, the contact switch108 of the button switch 1301 is pressed with a forward thrust of afinger. Compared with the press of the button switch 400 shown in FIG.4, the press of the button switch 1301 results from an unnaturalmovement of a finger. When the button switch 1301 is realized with aswitch means that is not clicked on or off, such as, a touch sensor, auser can maneuver the button switch with a good sense of touch

FIG. 5 is an enlarged view of an exemplary button 400. The button 400has a concave part 500 formed in a side thereof to contact a finger sothat the fingertip will fit within the concave part. Consequently, everytime a finger is inserted, the fingertip is relocated at the sameposition with higher accuracy. A positional deviation caused by a pressof the button 400 will not occur. As also shown in FIG. 4, the height ofthe button 400 is preferably limited to a value permitting only theventral part of a fingertip to lie on the button. A space is createdabove the button 400 so that the button can be pressed with a fingerhaving a long nail or having a false nail attached thereto.

FIG. 6 is an enlarged view showing an exemplary finger rest 402 formedto bear the root of a finger. The finger rest 402 may be a simpleplate-like projection. The simple plate-like projection is preferablymachined to have one side thereof dented like a semicircular recess sothat the depth of the semicircular recess will be a bit larger than thethickness of a finger. Consequently, a sideways displacement of a fingercan be naturally prevented. In this case, the finger rest 402 is notexactly an independent means but is a variant of the aforesaid guidegroove 112. The finger rest 402 thus fills the role of a guide thatdirects a user to place his/her finger in an appropriate position.

FIG. 7 shows an example of another variant of the identificationapparatus 100. In the example shown in FIG. 1, the light source unit 102is shaped like a roof in order to intercept illumination light comingfrom the ceiling or other external source. In the FIG. 1 case, however,since a user is asked to insert his/her finger in a shielded space, theuser may feel uneasy. For this reason, as shown in FIG. 7, the lightsource may be located obliquely above a finger, and a cover obstructingthe user's view of his/her finger is thus excluded. In the illustratedexample, a roof-like light source unit is extended obliquely from bothsides of an opening. A light source 106 is incorporated in each of thelight source units. The two light sources are distributed evenly aroundthe opening. This is because when one light source is included, lighttransmitted by a finger is polarized to create a light spot.Consequently, a correct hemal pattern may not be visualized.

FIG. 8 shows an example of another arrangement of optical elementsincluded in the identification apparatus 100. A light source 800provides reflective light while a light source 106 provides transmissivelight. These two light sources 106, 800 are turned on or off under thecontrol of a computer 204. At this time, the on or off states of thelight sources may be combined arbitrarily. For example, the reflectivelight source 800 generates visible light, and a camera 114 images thesurface of a finger. In the aforesaid embodiment, an optical filtertransmits near-infrared light alone. Instead, an optical filter 802 of avariable or switchable type is included herein. Namely, the operatingmodes of the optical filter 802 may be switched so that visible lightwill also be passed if necessary. This makes it possible to visualizethe features of a living body including the fingerprint on the surfaceof a finger. The feature of a living body detectable on the surface of afinger and a hemal pattern may be used in combination foridentification. This leads to improved precision in identification.

The advantages provided by the employment of the button switch in theidentification apparatus have been previously described. The action ofpressing a button signifies that a user touches the apparatus. It cannotbe said that there is no possibility that a user may loathe touching theapparatus from a sanitary viewpoint. This kind of a user's feeling canbe alleviated by the adoption of a generally used antibacterial materialfor the apparatus body or the button. Letters “antibacterial” to beinscribed in the apparatus body will produce a good psychological effecton a user. According to the configuration in which the present inventionis implemented, the sensor used to acquire a hemal pattern need not beexposed on the surface of the apparatus body. The surface of theapparatus can therefore be readily processed to be antibacterial.Living-body identification methods according to which a sensor must bebrought into direct contact with a living body have difficulty in makingthe sensor antibacterial. The present invention has overcome thedifficulty.

In the aforesaid embodiment, the button switch is realized with amechanical pushbutton. Alternatively, for example, electrostaticswitches that conduct when touched with a finger may be substituted forthe switches 400 and 108. Additionally, a combination of a light sourceand an optical sensor may be used so that when a fingertip comes to apredetermined position to thus intercept light, a switch will be turnedon. In this case, various types of sensors including a sensor sensitiveto presence of a human being can be utilized.

FIG. 14 shows a finger identification apparatus having a keypad. Even ifidentification using a finger fails, identification can be retried byentering a password, which is registered in advance, using keypad 140.Moreover, when identification using a finger and identification using apassword may be combined, more reliable identification can be achieved.Furthermore, an action to be performed after identification may bedifferentiated between identification using a finger and identificationusing a password.

According to the present invention, a finger is smoothly led to aspecific position, a hemal pattern of the finger is visualized, avisualized pattern in a produced image can be collated with registeredpatterns on a stable basis without the necessity of alignment orcorrection that is required due to turning of a finger. Moreover, theprobability that part of a hemal pattern is missing because a finger iscompressed will be reduced. This leads to improved precision inidentification.

Nothing in the above description is meant to limit the present inventionto any specific materials, geometry, or orientation of parts. Manypart/orientation substitutions are contemplated within the scope of thepresent invention. The embodiments described herein were presented byway of example only and should not be used to limit the scope of theinvention.

Although the invention has been described in terms of particularembodiments in an application, one of ordinary skill in the art, inlight of the teachings herein, can generate additional embodiments andmodifications without departing from the spirit of, or exceeding thescope of, the claimed invention. Accordingly, it is understood that thedrawings and the descriptions herein are proffered by way of exampleonly to facilitate comprehension of the invention and should not beconstrued to limit the scope thereof.

1. A personal identification apparatus, comprising: a light source toradiate a light to a finger, a planar member which is arranged so thatthe light source may be enclosed, a marking part which is formed on asurface of the planar member, an imaging unit for creating an imagebased on the light from the light source, and a processing unit, whereinthe processing unit calculates a position of the marking part hidden bythe finger based on the image.
 2. A personal identification apparatusaccording to claim 1, wherein the processing unit calculates a thicknessof the finger measured between a left side portion of the finger and aright side portion of the finger.
 3. A personal identification apparatusaccording to claim 1, wherein when a direction to a surface of a ball ofthe finger from a back of the ball is downward, the finger is locatedlower than the light source and higher than the imaging unit.
 4. Apersonal identification apparatus according to claim 1, wherein theprocessing unit extracts a vein pattern from the image by the imagingunit and matches the vein pattern with a registered pattern.
 5. Apersonal identification apparatus according to claim 1, wherein themarking part has a material which can reflect light from the lightsource more than the material of the planar member.
 6. A personalidentification apparatus, comprising: a light source to radiate a lightto a finger, a reflection suppression member which is arranged so that alight source may be enclosed, a marking part which is formed on asurface of the reflection suppression member, an imaging unit forcreating an image based on the light from the light source, and aprocessing unit, wherein the processing unit calculates a position ofthe finger from a brightness difference of the marking part and aportion of the reflection suppression member based on the image createdwith the imaging unit.
 7. A personal identification apparatus accordingto claim 6, wherein the processing unit calculates a thickness measuredbetween a left side portion of the finger and a right side portion ofthe finger.
 8. A personal identification apparatus according to claim 6,wherein when a direction to a surface of a ball of the finger from aback of the ball is downward, the finger is located lower than the lightsource and higher than the imaging unit.
 9. A personal identificationapparatus according to claim 6, wherein the processing unit extracts avein pattern from the image by the imaging unit and matches the veinpattern with a registered pattern.
 10. A personal identificationapparatus according to claim 6, wherein the marking part has a materialwhich can reflect light from the light source more than the material ofthe reflection suppression member.